# RE: Observation selection effects

From: Stathis Papaioannou <stathispapaioannou.domain.name.hidden>
Date: Sun, 03 Oct 2004 01:47:36 +1000

Eric Cavalcanti writes:

>From another perspective, I have just arrived at the
>road and there was no particular reason for me to
>initially choose lane A or lane B, so that I could just
>as well have started on the faster lane, and changing
>would be undesirable. From this perspective, there
>is no gain in changing lanes, on average.

Here is another example which makes this point. You arrive before two
adjacent closed doors, A and B. You know that behind one door is a room
containing 1000 people, while behind the other door is a room containing
only 10 people, but you don't know which door is which. You toss a coin to
decide which door you will open (heads=A, tails=B), and then enter into the
corresponding room. The room is dark, so you don't know which room you are
now in until you turn on the light. At the point just before the light goes
on, do you have any reason to think you are more likely to be in one room
rather than the other? By analogy with the Bostrom traffic lane example you
could argue that, in the absence of any empirical data, you are much more
likely to now be a member of the large population than the small population.
However, this cannot be right, because you tossed a coin, and you are thus
equally likely to find yourself in either room when the light goes on.

--Stathis Papaioannou

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Received on Sat Oct 02 2004 - 11:48:56 PDT

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